An optical transmission apparatus includes a wavelength variable filter whose transmission light wavelength is variable; a receiver that receives light, the light being sent from another optical transmission apparatus and passing through the wavelength variable filter; a transmitter that sends to the another optical transmission apparatus, a utilization permission request for a second wavelength corresponding to a first wavelength of the light received by the receiver, the transmitter sending the utilization permission request as light of the second wavelength and in a form of a tone signal of a predetermined frequency; and a controller that, when receiving from the another optical transmission apparatus, a utilization permission notification of the second wavelength for a sender of the utilization permission request, configures a wavelength of a main signal to the second wavelength, the main signal being sent from the transmitter to the another optical transmission apparatus.

The Bi-Di coherent transmission system is configured with at least one pair of modules coupled to one another via a single fiber. The modules each are configured with a pair of laser outputting two reference signals at respective different wavelengths ?.sub.1o and ?.sub.2o, photonic transceiver and a wavelength division multiplexer (WDM) coupler. The photonic transceivers each have transmitter and receiver branches integrated in a photonic circuit and receiving the reference signals. The transmitter is configured to modulate the received reference signals ?.sub.1oT and ?.sub.2oT which are further coupled into the WDM coupler. The WDM couplers each sort out one of the modulated signals and transmit the other modulated signal such that the transmitted modulated signal at different wavelengths ?.sub.1oT and ?.sub.2oT are coupled into respective opposite ends of the fiber and propagate towards one another in opposite directions. The transmitted modulated signals are coupled into respective branches through the WDM couplers with each transmitted modulated signal interfering with the reference signals at wavelengths ?.sub.1o and ?.sub.2o. The photodiodes of respective receiving branches are configured to detect a beat frequency of the interfering signals at the same wavelength.

Partial optimization systems and methods of wavelengths or spectrum in an optical network include, based on current services in the optical network each having a route and wavelength assignment and based on a ratio of services that can be changed in the partial optimization, preforming a first stage optimization to determine which of the current services are changed for one or more of the route and the wavelength assignment to attain a reduction of a number of wavelengths; performing a second stage optimization to determine an order of implementing changes from the first stage optimization that with the order minimizing one or more of conflicts and step counts; and causing implementation of the changes in the optical network.

It is an object to monitor signal flow (optically switched state) in an optical node without using a monitor light. In each of output ports of the optical node, a part of output signals is turned back, and the output signal light is subjected to intensity modulation or phase modulation, assigned port identification information, and allowed to reverse in the optical node. From an input port corresponding to the reversed output signal, a plurality of signals turned back are output. The plurality of signals are appropriately converted into intensity modulation from phase modulation and separated by a device having a spectroscopic function, and identification information is read out based on an intensity of a signal light for each signal, thereby determining an optically switched state to an output port corresponding to the input port.

A bidirectional, multi-wavelength fiber optical network that enables communication between electrical components (such as line replaceable units) at high data transmission rates. The proposed fiber optical network in accordance with some embodiments comprises a single plastic or glass optical fiber capable of transmitting data at rates faster than 1 Gbits/sec. In accordance with some embodiments, the number of fiber cables between line replaceable units onboard an airplane can be reduced by a factor of eight or more by substituting one gigabit plastic or gigabit glass optical fiber for four or more plastic or glass optical fibers.

A disclosed method for optimizing channel selection in a flexible grid of an optical network may be used to select a minimum number of channels to allocate to traffic between pairs of optical transponders at a particular distance based on the modulation format and the FEC mechanism used. The method may include selecting an initial number of channels to allocate to the traffic, tuning the modulation format for the traffic while potentially reducing the number of channels, and tuning the FEC mechanism for the traffic while potentially further reducing the number of channels. The transponders may support multiple modulation formats of different orders and an adaptive FEC mechanism for which the maximum number of FEC overhead bytes is equal to the number of bytes in the transmitted data packets. The method may be implemented by an SDN controller and may be dependent on a feedback mechanism between the optical transponders.

A system for optimizing power allocation for each optical transmitter in an optical transmission system, the system comprises at least two intensity modulated optical transmitters, each of which is controlled by a modulator; an optical channel that can be spatially multiplexed by a multiplexer; and at least two optical detectors, for detecting the transmitted modulated signals. Each of the modulators are adapted to modulate the transmitters such that the electrical power consumption of the optical transmitters is minimized by a modulation scheme of the modulators, that uses energy efficient convex optimization to multiplex the transmitted optical signals, by the multiplexer in a multiple-input-multiple-output (MIMO) scheme. Each of the modulators are adapted to modulate the transmitters such that the capacity is maximized by a modulation scheme of the modulators, that uses energy efficient convex optimization to multiplex the transmitted optical signals, by the multiplexer in a multiple-input-multiple-output (MIMO) scheme.

It is an object to monitor signal flow (optically switched state) in an optical node without using a monitor light. In each of output ports of the optical node, a part of output signals is turned back, and the output signal light is subjected to intensity modulation or phase modulation, assigned port identification information, and allowed to reverse in the optical node. From an input port corresponding to the reversed output signal, a plurality of signals turned back are output. The plurality of signals are appropriately converted into intensity modulation from phase modulation and separated by a device having a spectroscopic function, and identification information is read out based on an intensity of a signal light for each signal, thereby determining an optically switched state to an output port corresponding to the input port.

A communication method includes, in a state where first information equipment and second information equipment are communicatively connected via optical switches and an optical communication network, switching, by an optical switch to which the first information equipment is connected, a connection destination of the first information equipment from an input/output port connected to the optical communication network to a control port to which the control device is connected in response to a predetermined operation of the first information equipment, receiving, by the control device, information indicating third information equipment that is a communication connection destination different from the second information equipment via the control port of the optical switches from the first information equipment, allocating, by the control device, a wavelength used for communication to the first information equipment and the third information equipment based on information indicating the communication connection destination, and connecting, by the control device, the first information equipment to the third information equipment so as to be communicable by controlling connection of an input/output port of the optical switches.

The communication system has first and second optical systems and an optical feed fiber in communication with the first optical system and arranged to convey a feeder optical signal to the second optical system. The first optical system includes a multiplexer configured to multiplex/demultiplex between a first optical line terminal signal, a second optical line terminal signal, and the feeder optical signal. The feeder optical signal includes the first optical line terminal signal and the second optical line terminal signal. The first optical line terminal signal includes a first upstream free spectral range and a first downstream free spectral range. The second optical line terminal signal includes a second upstream free spectral range and a second downstream free spectral range. The second optical system is in communication with the optical feed fiber and is configured to multiplex and demultiplex between the feeder optical signal and optical network unit signals.